This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. We use X-ray crystallography, combined with other biophysical and biochemical methods, to study the structure and function of the Eph receptors and their interactions with the ephrin ligands. We also study the interactions of Ephs and ephrins with other binding partners, including the Henipavirus cell-attachment proteins.